MARTINEZ — Jurors began deliberating Wednesday in the murder trial of a former El Cerrito high school football star accused of shooting a Richmond resident inside a moving van.

Marshon Ardoin, 23, of Dixon, is charged with shooting David Mallard, 28, as the two rode in the van through Richmond in April 2016. Mallard’s body was found in an empty field in Bay Point, his pockets turned out and roughly $4,000 missing from his person.

But much of the prosecution’s case hinges on the word of two witnesses — Ardoin’s mother and their friend — who allegedly drove Mallard’s body from Richmond to Bay Point that evening and left it in the field, then drove to Vallejo to clean out the van. The defense argued that Ardoin’s former friend, who knew Mallard for years, was the real killer and had used Ardoin as a scapegoat.

Prosecutors contend Mallard was sitting in the front passenger seat of the van and Ardoin behind him when the shots were fired. Ardoin then allegedly fled the scene while his mother and the van’s driver made the trip to Bay Point, then back to Vallejo. They were both arrested, but weren’t charged after agreeing to cooperate with police.

The pistol used to kill Mallard was found in Dixon three months after officers arrested Ardoin at an apartment complex there. Skin cells found on the handle were matched to Ardoin, but there were also other DNA profiles too badly degraded for testing.

Ardoin’s mother told police her son fired the fatal shots, but changed her story on the witness stand. Ardoin’s attorney, Anna Teruel, told jurors she originally implicated her son because she had been told she’d be murdered next if she didn’t blame him.

“The two main prosecution witnesses are both liars,” she said.

During his closing argument, prosecutor Satish Jallepalli attacked the defense theory, saying it didn’t add up. He asked jurors to “channel your inner sociopath” and asked in an incredulous voice why Ardoin’s mother wasn’t murdered as well if Ardoin wasn’t the killer.

Jallepalli added that forensic evidence, like the positioning of the bullet holes, reinforced the theory that Ardoin sat behind Mallard and shot him.

“Apparently the laws of physics and chemistry and heat all joined the plot to frame (Ardoin),” he sarcastically told jurors.

Teruel said the acts of the van’s alleged driver were “the actions of a guilty person.” She said Mallard’s emptied pockets were evidence that the driver had stolen money from him while dumping the body. She said the man, if he really cared about Mallard like he later told police, could have driven to a hospital to get help, rather than driving to a field in Bay Point.

Ardoin’s mother, Teruel said, “begged for them not to kill her,” adding that was the only reason her life was spared.

“In exchange for her life, that’s why she falsely accused her son of murder,” Teruel said.

The motive, according to Jallepalli, was that Mallard was rumored to be involved in the 2008 killing of Ardoin’s relative.

But Teruel argued that the van’s driver was closer to the relative than Ardoin had been, and therefore had a greater motive to kill. She said Ardoin had gotten recruitment letters from the University of Oregon and other schools and wouldn’t have endangered his bright future by committing a homicide.